Dependence of the conversion of chlorophenols by rhodococci on the number and position of chlorine atoms in the aromatic ring

Study of the conversion of chlorophenols by Rhodococcus opacus 1G, R. rhodn ii 135, R. rhodochrous 89, and R. opacus Icp disclosed the dependence of th e conversion rate and pathway on the number and position of chlorine atoms in the aromatic ring. The most active chlorophenol converter, strain R. opa cus Icp, grew on each of the three isomeric monochlorophenols and on 2,4-di chlorophenol; the rate of growth decreased from 4-chlorophenol to 3-chlorop henol and then to 2-chlorophenol. The parameters of growth on 2,4-dichlorop henol were the same as on 3-chlorophenol. None of the strains studied utili zed trichlorophenols. A detailed study of the pathway of chlorophenol trans formation showed that 3-chloro-, 4-chloro-, and 2,4-dichlorophenol were uti lized by the strains via a modified ortho-pathway. 2-Chlorophenol and 2,3-d ichlorophenol were transformed by strains R. opacus Icp and R. rhodochrous 89 via corresponding 3-chloro- and 3,4-dichlorocatechols, which were then h ydroxylated with the formation of 4-chloropyrogallol and 4,5-dichloropyroga llol; this route had not previously been described in bacteria. Phenol hydr oxylase of R. opacus 1G exhibited a previously undescribed catalytic patter n, catalyzing oxidative dehalogenation of 2,3,5-trichlorophenol with the fo rmation of 3,5-dichlorocatechol but not hydroxylation of the nonsubstituted position 6.